Basic Arduino relay shield example

The Relay Shield features four high quality relays and provides NO/NC interfaces, four dynamic LED indicators to show the on/off state of each relay, and the standardized shield form factor to provide a smooth connection to Arduino compatible boards.

Relay Shield is a small current signal control module can achieve single chip to control large power device
Widely use in singlechip home device
Can be plug to the main board which is compatible with Arduino;
4-channel relay stand Arduino Shield interface;
3-M3 screw hole easy to install
Driven by 5V / 3.3V normally open contact close;
With red LED indicator onboard

Note:

Please avoid the green terminal short-circuit by the housing as connecting with Arduino UNO main board

In this example we will show how to use one of the relays on the shield to control an LED by switching it on and off.

Here is a picture of the relay shield

relay shield

J1 Interface/Terminal Pin Description:

COM1 (Common Pin) : The relay pin controlled from the digital pin.
NC1 (Normally Closed): This terminal will be connected to COM1 when the RELAY1 control pin (Digital 7 I/O pin) is set low and disconnected when the RELAY1 control pin is set high.
NO1 (Normally Open): This terminal will be connected to COM1 when the RELAY1 control pin (Digital 7 I/O pin) is set high and disconnected when the RELAY1 control pin is set low.

Schematic

Here is a simple picture showing how to connect the LED to the relay shield